KR20050057465A - Improvement in and relating to gas cleaning devices - Google Patents

Abstract

There is disclosed a gas cleaning device (4) comprising a gas inlet (6), a gas outlet (8) and a path of fluid communication (10) between the gas inlet and gas outlet, a filter (14) in the path of fluid communication and ionising means (16), which ionising means is at least partly within the filter. A vehicle (3) incorporating such a gas cleaning device in the exhaust gas flow path of an exhaust (2) thereof is also disclosed.

Description

Improvement in gas cleaning devices related to gas cleaning devices {Improvement in and relating to gas cleaning devices}

Internal combustion engines generate a wide range of contaminants in use. Carbon based contaminants are particularly problematic in that their particulate size causes serious health problems. Many attempts have been made to reduce the level of contaminants in the exhaust gas stream, focusing on clean combustion and the use of catalytic converters. However, it is still desirable to further reduce the level of pollutants, and many countries are considering legislation that would require a reduction in pollutant emissions, or at least benefit from the reduction.

It has been proposed to provide a device for removing contaminants in a vehicle exhaust. If that is done, it is generally desirable to keep the size of the relevant device in the vehicle to a minimum.

Preferred embodiments of the present invention aim to overcome or avoid the problems associated with the prior art, whether or not referred to herein.

The invention will now be described by way of example only, with reference to the following attached drawings.

1 is a schematic perspective view of a vehicle exhaust including a gas cleaning device according to the present invention.

2 is a cross-sectional view of a gas cleaning device according to a first aspect of the present invention.

3 is an enlarged view of a portion of FIG. 2 showing a filter opening.

4 is a cross-sectional view of a gas cleaning device according to a second aspect of the present invention.

5 is an enlarged cross-sectional view of an electrode mounting apparatus suitable for use in the present invention.

According to a first aspect of the invention there is provided a gas inlet, a gas outlet, a path of fluid communication between the gas inlet and a gas outlet, a filter and ionization means in the path of fluid communication, the ionizing means being at least An apparatus for cleaning gas in part within a filter is provided.

By providing the ionizing means at least partially in the filter, there is a substantial space saving.

Suitably, the ionization means is partly inside the filter and partly outside the filter. Suitably, the main part of the ionization means is in the filter.

Suitably, the ionization means is mounted on the outside of the filter. Suitably, the ionization means have a first end and a second end and are mounted only at the first end.

Suitably, the filter has a hollow tube and the ionization means protrude into the hollow tube.

Suitably, the ionization means comprises an electrode. Suitably, the electrode has elongated filaments.

Suitably, the filter has a filter opening and its leading edge is reversed.

Suitably, the device has an outlet tube at least partially in the filter. Suitably, the inlet to the outlet tube has an external truncated cone.

Suitably, the path of fluid communication has a first path through the filter and a second path to avoid the filter. Suitably, the second path is through the outlet tube opening.

Suitably, a return hole is provided in the outlet tube for the first flow path to join the second flow path. Suitably, the hole is small relative to the cross sectional area of the outlet tube.

Suitably, the filter has an electrically conductive layer proximate the filtration layer. Suitably, the conductive layer is inside the filtration layer. Suitably, the conductive layer comprises a gas permeable layer. Suitably the conductive layer comprises a metal layer. Suitably, the conductive layer is connected to a power supply, whereby the conductive layer can be electrically heated. Suitably, the conductive layer is coated at least partially in the less conductive layer.

According to a second aspect of the invention, there is provided a vehicle having a gas cleaning device according to the first aspect of the invention and a vehicle exhaust having a gas flow path in the exhaust gas flow path.

Referring to FIG. 1 of the drawings, there is shown a vehicle exhaust 2 of a vehicle 3 which is typically used in an internal combustion engine fueled with diesel or gasoline (gasoline). The exhaust part 2 is provided with the silencer 5. Included in the exhaust gas flow path of the vehicle exhaust is the gas cleaning device 4 according to the invention. The gas cleaning device 4 is located in the muffler 5.

Referring now to FIG. 2 of the drawings, the gas cleaning device 4 is generally located at the arrow 10 between the gas inlet 6, the gas outlet 8, and between the inlet 6 and the outlet 8. It has a fluid communication path indicated by.

Within the gas flow path is a hollow, circular, cylindrical tube filter element 14. Extending into the filter element 14 along the longitudinal axis is an electrode 16 connected to a high tensio power supply, schematically indicated at 18. Also within the filter element 14 is a gas outlet tube 20 which leads in part to the outlet 8.

The filter element 14 and the other components are supported by and mounted in the housing.

The filter element 14 has a circular cylindrical hollow tube of gas permeable filter material 24 for removing (at least partially) contaminants from the gas flow therethrough. Suitable filter material is NEXTEL ™ sold by 3M. The inner exposed surface of the filter material has a gas permeable and electrically conductive metal layer 26 having a plurality of holes therethrough substantially to allow free flow of gas and particulates. The metal layer 26 is coated with a less conductive coating (relative to the metal layer), such as the inner portion of the outlet tube 20 protruding into the filter element 14. Less conductive coatings are organic coatings, which act as resistive barrier coatings. A suitable coating is TLHB / 02 from Camcoat Performance Coatings, 127 High Street, Werington WA5 5LR, Viewsey Industrial Estate, UK.

At the electrode end of the filter element 14, the metal layer 26 terminates with an opening 28 of the filter with an inverted edge 30, which is well illustrated in FIG. 3. The housing 22 has a gas impermeable wall 32 in which a filter opening 28 is fixed. At the outlet end of the filter element 14 the metal layer 26 ends with an insulating collar 34 formed from a ceramic material.

Extending from the filter element 14 through the housing 22 is the electrical contact 36 and the thermocouple 38. The electrical contact 36 is connected to a power supply 37 of 12 volts (eg, a vehicle battery) for heating the periodic metal layer 26 to burn off accumulated particulates from the filter material 24. Thermocouple 38 may be used to monitor the exhaust gas temperature.

The outlet tube 20 is generally circular cylinder and hollow and is mounted along the longitudinal axis of the filter element 14 such that the electrode 16 and the outlet tube 20 are substantially aligned. The outlet tube 20 has a truncated cone shaped opening 40. The outlet tube 20 extends through the housing 22 to the gas outlet 8.

The mode of operation of FIG. 2 in accordance with an embodiment of the present invention will now be described. For the purposes of this description it is convenient to divide the apparatus 4 into two separate chambers, which are the inlet chamber 42, the chamber 44 in the filter and the chambers 45 after the filter. The inlet chamber 42 is before gas flow enters the filter 14. The chamber 44 in the filter is a volume in the filter 14. The chamber 44 after the filter is an annular volume around the filter 14 and at its end it is outside of the gas outlet tube 20.

In use, the electrode 16 is maintained at a relatively high direct current voltage, typically at 35 kV. When the apparatus 4 is in the vehicle exhaust gas flow, the exhaust gas enters the apparatus 4 and enters the inlet chamber 42 through the gas inlet 6 and the only outlet from the inlet chamber is through the filter opening 28. To filter 14. During the time that the exhaust gas is consumed at the upstream end of the inlet chamber 42 and the filter 14, the gas and the attendant particulates are close to the charged electrode 16, which is a meaningful source of particulates in the gas flow stream. It acts as an ionization means to ionize the ratio. Ionized particulates are attracted to the metal layer 26 inside the filter element 14. The particulates are combined with existing downstream momentum, which means that the particulates tend to flow along the filter element 14 towards the metal layer 26. By the momentum that the particles have, and to the extent that they are transported by a gas flow generally downstream, the particles pass through the metal layer 26 through a plurality of holes, and where the particles are captured and cleaned from the gas stream, the filter element ( 14 into the filter material 24. Thus, the gas passing through the filter element 14 has particle contaminants at least partially removed therefrom.

The other outlet from the in-filter chamber 44 is through the gas outlet tube 40. The gas may flow freely into the gas outlet tube 20, but a substantial portion thereof from the in-filter chamber 44 because it has been attracted and ionized away from the central gas flow stream passing into the gas outlet tube 20. The gas thereby tends to have a highly reduced particle concentration.

The gas passing through the filter 14 may enter the chamber 46 after the filter around the filter element 14 and re-enter the gas flow flow to the outlet by a hole 48 in the gas outlet tube 20. .

Thus, from the inlet 6, into the inlet chamber 42, into the filter chamber 44, through the filter 14, into the chamber 46 after the filter, through the hole 48, the gas outlet tube 20. There is a first gas flow path to the outlet 8. A second gas flow path is provided to the outlet 8 from the inlet 6, into the inlet chamber 42, into the filter chamber 44, and back to the outlet 8 as a gas outlet tube 20. The gas flow path does not pass through the filter 14 and avoids it. This helps to avoid constructing excessive back pressure.

The organic coating appears to prevent the charged particulates from discharging upon contact with the metal layer 26. If they do, they can return back into the main gas flow and are not filtered.

Such a device is believed to be advantageous for removing carbon particulate contaminants from the exhaust gas stream.

The inverted flange 30 of the filter opening 28 ensures that something is interposed between the electrode 16 and the free end to avoid arc discharge where charge is concentrated at the free end of the filter opening 28.

The truncated cone 40 at the inlet to the gas outlet tube 20 acts to deflect particulates flowing in the center to the filter element 14, avoiding the free end appearing at the electrode 16 and again causing arc discharge. Evade.

Referring to FIG. 4 of the accompanying drawings, the apparatus 4 is substantially similar to that shown in FIG. 2 except that the electrode 16 and the gas outlet tube 20 are positioned in different configurations in the longitudinal direction.

Referring to FIG. 5 of the accompanying drawings, there is shown an electrode mounting apparatus suitable for all of the above described embodiments of the present invention. The ceramic electrode mounting portion 50 holds the electrode 16 in the center thereof. The electrode mount 50 has a plurality of protrusions 52 along its length to minimize the risk of a short circuit. The electrode 16 is mounted only at one end thereof.

One or more of the devices shown in use may be used in series or in parallel. The overall size of the unit can be scaled to suit the application. Although described as being used in connection with being applied to the exhaust of a vehicle, the apparatus can be used in many gas cleaning operations. It is not necessary for the devices according to the invention to remove all contaminants or all kinds of contaminants or any one contaminant. Some contaminant concentrations may remain unchanged in practice.

Many small variations on the components and their relative positions can be made. For example, the position of the gas outlet tube cone 40 can be modified along the interior of the filter element 14; The distance between the electrode 16 and the gas outlet tube 20 can vary. The diameter and size of the filter 14 can be varied in relation to the size and location of the gas outlet tube cone 40, the deflection angle, the aperture and the distribution of the gas outlet tube cone 40; The gas outlet tube 20 may vary in length and diameter; The gas reentrant holes 48 may vary in size and shape, and several such gas reentrant holes may be provided; The filter material can vary in thickness and type; The filter opening 28 may be equal to, larger than, or smaller than the filter diameter.

By providing the filter 14 around the electrode 16 rather than providing it downstream as a separate unit, the size of the device is much reduced.

Readers should refer to all documents and documents submitted concurrently with or prior to this specification with respect to the present application and published publicly for viewing with this specification, the contents of which are incorporated herein by reference. .

All features disclosed in this specification (including the appended claims, abstracts and drawings) and / or all steps of any method or process so disclosed are at least some of the features and / or combinations of which are mutually exclusive. Except, may be combined by any combination.

Each feature disclosed in this specification (including the appended claims, abstract and drawings) may be replaced by other features serving the same, equivalent or similar purpose unless expressly stated otherwise. have. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not limited to the details of the previous embodiments. The present invention is directed to any novel one, or any novel combination of features disclosed in this specification (including any appended claims, abstract and drawings), or to any of the steps of any method or process so disclosed. Extends to any new one, or any new combination.

The present invention can be applied to an exhaust device of a vehicle and the like.

Claims (22)

A gas inlet, a gas outlet, a path of fluid communication between the gas inlet and the gas outlet, a filter in the path of fluid communication and ionization means, the ionizing means being at least partially within the filter. Gas cleaning device. The method of claim 1, And the ionization means is partly in the filter and partly outside the filter. The method of claim 2, A gas cleaning device, wherein the main part of the ionization means is in a filter. The method of claim 2 or 3, The gas cleaning device, characterized in that the ionization means is mounted outside the filter. The method of claim 4, wherein And the ionization means has a first end and a second end and is mounted only at the first end. The method of claim 1, wherein The gas cleaning device according to claim 1, wherein the filter has a hollow tube and protrudes ionization means therein. The method of claim 1, wherein An ionization means is provided with an electrode, The gas cleaning apparatus characterized by the above-mentioned. The method of claim 7, wherein And the electrode has elongated filaments. The method of claim 1, wherein And wherein the filter has a filter opening and the leading edge of the filter opening is reversed. The method of claim 1, wherein And the apparatus further comprises an outlet tube at least partially in the filter. The method of claim 10, The inlet to the outlet tube has an external truncated cone, characterized in that the gas cleaning device. The method of claim 1, wherein The path of fluid communication comprises a first path through the filter and a second path that avoids the filter. The method of claim 12, And the second path is through the outlet tube opening. The method of claim 1, wherein A gas cleaning device, characterized in that a return hole is provided in the outlet tube for the first flow path to join the second flow path. The method of claim 15, And the hole is small compared to the cross sectional area of the outlet tube. The method of claim 1, wherein And wherein the filter comprises an electrically conductive layer proximate to the filtration layer. The method of claim 16, The conductive layer is inside the filtration layer, The gas cleaning device characterized by the above-mentioned. The method according to claim 16 or 17, A conductive layer is provided with a gas permeable layer, The gas cleaning apparatus characterized by the above-mentioned. The method according to any one of claims 16 to 18, A conductive layer is provided with a metal layer, The gas cleaning apparatus characterized by the above-mentioned. The method according to any one of claims 16 to 19, And a conductive layer is connected to the power supply, whereby the conductive layer can be electrically heated. The method according to any one of claims 16 to 20, And the conductive layer is at least partially coated with a less conductive layer. A vehicle having a gas cleaning device according to the preceding term in a exhaust gas flow path and a vehicle exhaust having an exhaust gas flow path.